Internal combustion engine



y 1934- A. w. POPE, JR ,960,795

INTERNAL COMBUSTION ENGINE Filed June 29, 1933 Patented May 29, 1934 UNITED STATES INTERNAL COMBUSTION ENGINE Arthur W. Pope, Jr., Waukesha, Wis., assignor to Waukesha Motor Company, Waukesha, Wis., a corporation of Wisconsin Application June 29, 1933, Serial No. 678,155

16 Claims.

This invention relates to internal combustion engines, and has to do more particularly with a system and method for starting injection internal combustion engines.

It is known to use glow plugs in starting high speed injection engines. These glow plugs are analogous to spark plugs, but, instead of being provided with a spark gap, have coils of resistance wire disposed within the combustion space of the engine. These coils are heated to suitable temperature for igniting the fuel charge, by flow of an electric current therethrough. The use of coils made of small or fine wire is objectionable because such coils do not rapidly dissipate the heat generated by combustion of the fuel within the engine and, for this reason, have a relatively short life. It is desirable, therefore, to use glow plugs adapted to operate on a low voltage circuit of approximately two volts, since these low voltage plugs can employ coils made of relatively heavy wire and which are able to withstand the heat generated in the combustion space of the engine.

When low voltage glow plugs are used in accordance with present practice, it is necessary to provide a low voltage battery for these plugs, in addition to the high voltage battery for operating the starting motor. This is open to the objection that it necessitates the use of two batteries of different voltages and leads to complications in charging these batteries. It is also possible to use low voltage glow plugs connected in series with a high voltage battery for operating the starting motor, but this is open to the objection that the reliability of operation is decreased since the failure of one plug will render inoperative all of the other plugs connected in the series. Also, the use of low voltage glow plugs connected in series is objectionable in that it necessitates the provision of incorporating terminals for the series connection, complicating the construction of the plugs and the circuit therefor.

In all of the starting systems with which I am familiar, which employ glow plugs, these plugs are included in a circuit independent of the starting motor circuit and controlled by an independent switch. The plugs are designed to be heated to their maximum temperature, without danger of melting, when the battery connected to these plugs is capable of delivering its maximum current, that is, under warm weather conditions. In cold weather, the eiiiciency of a battery is materially reduced so that the plugs are not heated to maximum temperature. It will be seen, therefore, that under present practice the coils of the glow plugs are heated to maximum temperature only in warm weather, when starting of the engine is not difficult and heating of the coil plugs to maximum temperature is unnecessary. On the other hand, during cold weather, when starting of the engine is difficult and maximum heating of the coils of the plugs is desirable, the plug coils are not heated to their maximum extent and difficulty in starting the engine is frequently encountered.

One of the main objects of my invention is to provide a starting system which avoids the above noted objections to the present practice. A further object is toprovide a system which permits the use of low voltage for the glow plugs from a high voltage starting motor battery without resorting to series connection of the glow plugs, and in which the closing of the starting motor battery circuit automatically closes the circuit 01" the glow plugs. It is also an object of my invention to provide a system in which the flow of current to the glow plugs is automatically regulated in such manner that the temperature of the coils of the plugs is increased and decreased as conditions require, the coils being heated to a higher temperature when the engine is cold and to a lower temperature when the engine is warm and easy to start. An additional object of my invention is to provide a method in which the flow of current to the coils of the glow plugs is automatically controlled in accordance with requirements. Further objects and advantages of my invention will appear from the detail description.

In the drawing:

Figure 1 is a diagram illustrating a starting system embodying my invention;

Figure 2 is a diagram illustrating a modified form of starting system embodying my invention. 95

In Figure 1 I have indicated an injection in ternal combustion engine E provided with a plurality of glow plugs 1 of known type, each plug including a coil 2 of resistance wire. These plugs have one terminal grounded at 3 and the other 100 terminal connected to a lead 4, the plugs being thus connected in multiple circuits. Lead 4 is connected to one pole of a starting motor M, the other pole of which is connected to terminal 5 of a starting motor switch S. This switch com- 105 prises a blade 6 connected to a terminal 7 which is connected by a lead 8 to one side of a battery B. The other side of this battery is grounded at 9 by a lead 10. A generator G, driven from the engine in a known manner, is connected to 110 leads 8 and 10 for charging the battery, and a cut-out switch C of known type is disposed in the generator circuit for cutting out the generator when it is driven below proper speed for charging the battery.

The glow plugs are designed to operate satisfactorily on a current having a potential of approximately two volts, when the engine is warm and easy to start, as in warm weather, but these plugs and the starting motor are so de- 120 signed that, with the motor stalled, the relative resistances of the starting motor and the glow plug circuit is such that the glow plugs are heated to their maximum designed limit. Since the glow plugs are connected in series with the motor and the battery, current from the battery is delivered to the glow plugs through the motor. When the engine is cold and hard to start, as in cold Weather, a heavy load is imposed upon the starting motor and, consequently, a correspondingly heavy current flows from the battery through this motor and to the glow plugs. As a result, the maximum glow plug temperature is attained when the speed of the starting motor is at the minimum and high temperature of the coils of the glow plugs is desirable, as in starting the engine in cold weather. As the speed of the starting motor increases, its counter E. M. F. increases and the flow 01' current to the glow plugs decreases. This provides an automatic control of the current flow to the glow plugs by the starting motor, and in accordance with requirements.

In the system illustrated, it is assumed that the motor requires a current having a potential of ten volts when the motor is operating at normal cranking speed, and that the battery has a potential of 12 volts. This means that, under ordinary warm weather operating conditions, a current having a potential of approximately two volts will be delivered to the glow plugs since, when the engine is easy to crank, the starting motor quickly attains normal cranking speed. The system of my invention assures, therefore, that the coils of the glow plugs will be heated to maximum temperature to facilitate starting of the engine under adverse conditions, as in cold weather, and will be heated to a lower temperature sufiicient for starting the engine under favorable conditions, as in warm weather. Since the glow plugs are in series with the motor and the battery, the starting switch S serves to automatically close the glow plug circuit simulta neously with closing of the starting motor circuit, thus eliminating any necessity for operating a separate switch controlling the glow plugs. The system is thus automatic so far as the glow plug circuit is concerned, it only being necessary for the operator to close the switch 3 when starting the engine.

I have shown a variable resistance R of known type connected to lead 4 between the glow plugs and the motor, this resistance being grounded and in shunt with the glow plugs. This resistance can be adjusted to relieve the glow plug circuit of any desired portion of the current flowing from the motor. For instance, if it be desired to use a starting motor requiring a higher voltage current, and a higher voltage battery, the resistance can be adjusted so that the maximum flow of current to the glow plugs is within the limit for which the plugs are designed, the operation of the system being the same as above described. The provision of this shunt resistance is also advantageous as providing means for controlling the maximum glow plug temperature to meet the requirements of diiferent fuels, some of which may require a higher temperature of the glow plug coils for starting than others.

In the system illustrated in Figure 2, I provide a battery bank B which comprises a high voltage portion for driving the starting motor and a low voltage portion for supplying current to the glow plugs. Starting switch S comprises three terminals 11, 12 and 13, and a blade or member 14 for interconnecting these three terminals. Terminal 11 is connected to lead 4, terminal 12 is connected by lead 15 to one pole of the starting motor M, the other pole of which is connected by lead 16 to one side of the battery bank 13, and terminal 13 is connected by lead 17 to the other side of the motor portion of the battery bank. The other side of the battery bank is grounded at 9 through a lead 10. Lead 17 is of low resistance relative to the glow plug circuit in order to prevent flow of current from the motor portion of the battery bank to the glow plugs. The motor portion and the glow plug portion of the battery bank are so related that there is no difference in potential therebetween when the motor M is operating at normal cranking speed, at which time the glow plugs are connected in series with the motor and the battery bank.

In the diagram of Figure 2, it is assumed that the motor requires a current having a potential of 10 volts when operating at normal speed for cranking the engine. The motor portion of the battery bank has a potential of 12 volts, and the plug portion has a potential of two volts. When the motor is operating at normal cranking speed, no difference in potential exists between the two portions of the battery bank and the glow plugs are connected in series with the motor and the battery bank, as noted. When the starting switch S is closed, the motor circuit is closed and the glow plug circuit is simultaneously closed, it being noted that the glow plugs are designed for maximum operating efficiency when used with a current having a potential of two volts. A gen-- erator G is connected to the opposite sides of the battery bank B and delivers charging current thereto at proper potential, when driven at proper speed. An automatic cut-out switch 0 is disposed in the generator circuit, as in Figure 1.

In both of the starting systems illustrated, the plugs are connected in series with the motor and the battery when the motor is driven at normal speed for cranking the engine. In the system shown in Figure 1, the flow of current to the glow plugs is automatically regulated by the starting motor and to suit requirements, the coils of the glow plugs being heated to a higher temperature under adverse starting conditions than under favorable starting conditions. The system of my invention thus provides a starting method in which the flow of current to the glow plugs is controlled by the starting motor, the current delivered to the plugs being decreased as the motor speed increases. This is a distinct advantage, as above pointed out. A further advantage in the method of my invention is that the motor circuit and the glow plug circuit are simultaneously closed, the flow of current to the glow plug circuit being controlled by the motor in the manner pointed out.

As above indicated, and as will be understood by those skilled in the art, changes in construction and arrangement of parts of the invention may be resorted to without departing from the field and scope of the same, and I intend to include all such variations, as fall within the scope of the appended claims, in this application in which the preferred forms only of my invention are disclosed.

What I claim is:-

1. In a starting system for internal combusseries relation with each other and with said plugs.

2. In a starting system for internal combustion engines, a plurality of glow plugs connected in multiple circuits, a battery, and a starting motor, the motor and the battery being connected in series relation with each other and with said plugs when the motor is driven at normal speed for cranking the engine.

3. In a starting system for internal combustion engines, a plurality of glow plugs connected in multiple circuits, a battery, a starting motor connected to the battery, and connections between the plugs and the motor and the battery for varying the flow of current from the latter to the plugs in accordance with variations in flow of current from the battery to the motor.

4. In a starting system for internal combustion engines, a plurality of glow plugs connected in multiple circuits, a battery, a starting motor, the motor and the battery being connected in series relation with each other and with the plugs, and a resistance in the plug circuit for determining the maximum flow of current to the plugs.

5. In a starting system for internal combusion engines, a plurality of glow plugs connected in multiple circuits, a battery, a starting motor, the motor and the battery being connected in series relation with each other and with the plugs, and a variable resistance connected in shunt with the plug circuit 6. In a starting system for internal combustion engines, a plurality of glow plugs connected in multiple circuits, a starting motor, a motor battery connected to said motor, a battery of relatively low voltage connected in series with the motor battery, and means for closing the motor circuit and simultaneously connecting the plugs to the low voltage battery.

7. In a starting system for internal combustion engines, a plurality of glow plugs connected in multiple circuits, a starting motor, a battery bank having one portion thereof connected to the motor and the remaining portion of relatively low voltage and connected to the plugs, and means for closing the motor circuit and simultaneously connecting the plugs to the low voltage portion of the battery bank, the two portions of said battery bank being so related that the plugs are connected in series with the motor and the battery bank when the motor is operating at normal speed for cranking the englue.

8. In a starting system for internal combustion engines, a plurality of glow plugs, a lead connected to one terminal of the respective plugs, the other terminal of the respective plugs being grounded and said plugs being connected in multiple relation, a starting motor, a battery bank comprising a motor portion and a plug portion of relatively low voltage, a lead connecting one terminal of the battery bank to one pole of the motor, a switch comprising three terminal elements and means for interconnecting the same, one of said elements being connected to said lead, a lead connecting a second terminal element to the other pole of the motor, and a lead connecting the other terminal of the motor portion of the battery bank to the third terminal element, the other terminal of the battery being grounded.

9. In a starting system forv internal combustion engines, a plurality of glow plugs connected in multiple circuits, a starting motor, a battery bank having one portion thereof connected to the motor and the remaining portion of relatively low voltage and connected to the plugs,

means for closing the motor circuit and simultaneously connecting the plugs to the low voltage portion of the battery banks, and a generator connected to the terminals of the battery bank.

10. In a starting system for internal combustion engines, a plurality of glow plugs, a lead connected to one terminal of the respective plugs, the other terminal of the respective plugs being grounded and said plugs being connected in multiple relation, a starting motor, a battery bank comprising a motor portion and a plug portion of relatively low voltage, a lead connecting one terminal of the battery bank to one pole of the motor, a switch comprising two contacts and a bridging member connected to the first mentioned lead, a lead connecting the other pole of the motor to one of the contacts, and a lead of relatively low resistance connecting the other terminal of the motor portion of the battery bank to the other of said switch contacts, the other terminal of the battery bank being grounded.

11. In a starting system for internal combustion engines, a plurality of glow plugs, a lead connected to one terminal of the respective plugs, the other terminal of the respective plugs being grounded and said plugs being connected in multiple relation, a starting motor, a battery bank comprising a motor portion and a plug portion of relatively low voltage, a lead connecting one terminal of the battery bank to one pole of the motor, a switch comprising two contacts and a bridging member connected to the first mentioned lead, a lead connecting the other pole of the motor to one of the contacts, a lead of relatively low resistance connecting the other terminal of the motor portion of the battery bank to the other of said switch contacts, the other terminal of the battery bank being grounded, and a generator connected to the terminals of said battery bank.

12. The method of starting an internal combustion engine employing a starting motor and glow plugs, which comprises simultaneously closing the motor circuit and the plug circuit, and controlling flow of current to the plugs by the current flow to the motor.

13. The method of starting an internal com bustion engine employing a starting motor and glow plugs, which comprises simultaneously closing the motor circuit and the plug circuit, and varying the flow of current to the plugs in inverse ratio to the motor speed.

14. The method of starting an internal combustion engine employing a starting motor and glow plugs, which comprises simultaneously closing the motor circuit and the plug circuit, and controlling flow of current to the plugs by the counter E. M. F. of the motor incident to operation thereof.

15. The method of starting an internal combustion engine employing a starting motor and glow plugs, which comprises simultaneously closing the motor circuit and the glow plug circuit, delivering current from the motor to the plugs and dividing among the plugs the delivered current, and decreasing the current delivered to the plugs as the motor speed increases.

16. The method of starting an internal combustion engine employing a starting motor and glow plugs, which comprises closing the motor circuit and the plug circuit, and controlling flow of current to the plugs by the operation of the motor. ARTHUR W. POPE, JR. 

